why does drinking alcohol make you sleepy

Beer, wine and other alcoholic beverages have somewhat of a split personality in how they affect people s brains. At first, the drinks tend to make people feel super sleepy, but they then jolt those same people wide awake and make them jittery just a few hours later. What s behind this odd effect? The answer has to do with alcohol s powerful effects on the central nervous system, said A. Leslie Morrow, a professor of psychiatry and pharmacology at the University of North Carolina School of Medicine. Alcohol enters the bloodstream quickly, usually within about 20 minutes of a person drinking it. It s a small molecule, so once alcohol is in the bloodstream, it can easily cross the blood-brain barrier and affect brain cells, known as neurons, Morrow said. [ In the brain, alcohol targets protein molecules, including GABA-A receptors, which are present on more than 80 percent of all neurons. Normally, these receptors are the destination for GABA (gamma-aminobutyric acid), a neurotransmitter (chemical messenger). Typically, GABA binds to these receptors and opens a channel, letting chloride ions move inside of neurons. Once chloride ions enter a neuron, they act like light-switch dimmers, slowing down that neuron s firing. When you reduce neuronal firing, that causes relaxation, sedation, sleepiness, Morrow told Live Science. If drops too much, it can cause coma and ultimately death, she said. Alcohol enhances this effect, she explained. That s why when people drink alcohol, they feel more relaxed, more sedated and sleepier than usual. They might have motor incoordination, Morrow added. They might forget where they parked their car. They might not be able to concentrate on their homework. If a person has a high alcohol tolerance, it might take a few more drinks for them to feel this way, Morrow noted. This explains why people with a low tolerance tend to feel these effects, including sleepiness, sooner than people with a. Credit: A. Leslie Morrow But why does alcohol also disrupt sleep? Once again, the answer involves GABA-A receptors and neurons. Within about 4 to 5 hours of social drinking (having about three drinks at an event), alcohol molecules in the brain cause GABA-A receptors to loose sensitivity to alcohol and to GABA itself.

When this happens, GABA-A receptors move from the surface of the neuron to the inside of the neuron, where they are degraded, Morrow said. This process is called receptor trafficking, she said. Once GABA-A receptors are inside of the neuron, neither GABA nor alcohol can activate them, Morrow said. Without these keys to let in chloride ions and slow down neuronal firing, the neurons get excited, than usual, she said. That s when we wake up, Morrow said. This effect depends on dose of alcohol and time after alcohol is consumed. The higher the dose of alcohol, the greater the effect on sleep and waking, since there is both a greater effect on neuronal inhibition and then on receptor trafficking inside the neurons. Luckily, the body can synthesize new receptors and insert them back on the surface of neurons within a few hours, Morrow said. [ This process happens differently for alcoholics, however, Morrow said. They ve lost so many GABA receptors that they re not making new ones at the same rate anymore, Morrow said. If they have fewer receptors, they re likely to be anxious [and] nervous, have dysphoria [a state of feeling unwell], and have trouble sleeping, just in general. That s what drives them to want to drink more. That perpetuates more drinking, and it leads to a vicious cycle. Morrow noted that alcohol s effects on the brain are much more complicated than described here. Since alcohol acts on many proteins, other proteins also contribute to its inhibitory activity in the brain, as well as the excitation that, she said. [But] GABA-A receptors are very sensitive to alcohol, and [they] play a major role in the mystery of alcohol s actions. If people wake up in the middle of the night after an evening of drinking, they should try relaxation techniques, such as deep breathing, to calm down, Morrow said. This can help keep feelings of mounting anxiety at bay, she said. You can obviously rev yourself up and make yourself more excited, Morrow said.

Realize that it s OK to rest. That if you can t sleep, that resting is good enough. Do things to, then your next day probably will be fine. Original article on. You probably know the feeling: a beer or two in, you start feeling much more relaxed, perhaps a little uninhibited. Eventually, though, you start to feel sleepy. Sooner or later you pass out, only to wake up a few hours later feeling tired and restless. Booze has a way of making people feel tired, but paradoxically, it can also make it difficult to fall asleep. Prior to the development of modern neuroscience, no one ever really understood why. New discoveries have shed some light on why has such distinct effects on the brain. As with any other system in the body, the answer to the question of why alcohol does what it does to your brain can be found in biochemistry. Alcohol affects protein compounds in the brain, including the receptors for a neurotransmitter called. Over 80 percent of neurons (brain cells) in the human brain contain receptors for GABA-A, which means that the majority of them will be affected by alcohol. What happens is that the alcohol will bind with these GABA-A receptors and allow chloride ions to pass into the brain cell. This causes the neurons firing of electrical signals to slow down, which manifests itself as the sensation of being tired, woozy and relaxed. The more this process continues, the drunker that person will become, and, over time, the more tired they will feel. If neuronal firing slows down too much, the person could fall into a coma or die, but most people stop drinking long before it gets to that point. This interference with neuronal function will also produce the poor physical coordination and difficulties with memory and concentration that are associated with intoxication. You might be thinking, Okay, weve established why alcohol makes you sleepy. But how is it possible that the same the chemical that induces sleepiness can also disrupt sleep? It turns out that GABA-A and its receptors are the key to unlocking this mystery as well.

After a few hours of exposure to alcohol, something significant happens to GABA-A receptors. The receptors become desensitized to both the GABA-A and the alcohol. As a result, the receptors retreat from into the center, a process known as receptor trafficking. Heres where it gets interesting: once these receptors have relocated inside the brain cell, theyre no longer able to be affected by the alcohol or GABA-A, and cant let more chloride ions inside the cell. Since there are no more chloride ions entering the cell and slowing down neural firing, the brain cell begins firing neural impulses faster than they normally would. This is what happens when the person who had been drinking now finds themselves restless and unable to sleep. Someone with a normal, healthy brain can produce new neurons within a few hours and recover from this process. Someone affected by alcoholism, however, will have difficulty synthesizing new GABA-A receptors quickly enough, and theyre much more likely to experience negative effects of alcohol withdrawal, such as anxiety and dysphoria, according to Professor Leslie Morrow at the University of North Carolina School of Medicine. Whats the takeaway from all this? Now that you know exactly how alcohol consumption affects your brain, be mindful of how much you drink! Its okay to drink alcoholic beverages in moderation, but understand your own tolerance for alcohol, and be aware of the alcohol content of the drinks you choose to consume. Many drinks, particularly shots or cocktails with lots flavoring, may good down much smoother than straight liquor. Its easy in such cases to take in a lot more alcohol than you intended to. Know your body and use common sense. READ ALSO:P The brain is an amazing tool, but chemical compounds from the foods and drinks we enjoy can influence it in positive or negative ways. If you want to be mentally sharp and clear, make sure youre eating and drinking quality nutrients, and not just junk food and drugs (alcohol is a drug). Your body and brain will thank you for it. References: